Recent EPA regulations with respect to vapors emitted during fueling of automobiles, trucks, etc. will require the recovery of these vapors during fuel dispensing. This recovery can be as high as 90% efficiency, or a release of no more than 0.4 grams of vapors per gallon of fuel dispensed.
Several systems have been proposed to recover these vapors during fueling. Among these have been vacuum assisted vapor withdraw and compression refrigeration condensation systems. One problem becomes apparent when considering any vapor recovery system. This is the ability to effect a tight seal between the gasoline or fuel dispensing nozzle and the tank filler neck. To complicate matters, there are no standard dimensions for tank filler necks on present automobiles. In fact, differences in size are required to prevent the addition of leaded fuels into automobiles that require unleaded fuels.
As disclosed in Vehicle Refueling Emissions Seminar American Petroleum Institute Publication 4222, several proposals have been put forth to effect this seal. All have so far required extreme operator attention to be effective. One device so disclosed in this publication (page 96) consists of a seal made on the inside of the tank filler neck by an expanding rubber annulus. The seal is made by actuating a lever. The present invention improves on this design by providing means for expanding and contracting this annulus without operator attention to levers, etc., thereby improving reliability of use and simplicity of design.